The church that Constantine built over the grave of St. Peters, 1450

We all know that during the 4th century the emperor Constantine constructed a Roman basilica over the grave of St. Peter. This was replaced during the renaissance with the current structure, as the old church had become structurally unsound during the interval.

It would be interesting to know the authorities on which this drawing was based. Are there, indeed, old sketches of the basilica? There surely ought to be! And it was a Roman basilica, preserved intact, so should be of interest to classicists.

I had a professor of late antique art who mentioned that, when Old St. Peter’s was disassembled, a careful record was kept of every piece for posterity. And this record (which must be vast) still exists. I don’t know anything more about it that that, but if such a thing were true, it might offer the possibility of creating an accurate model.